Federal Agencies Deliver Blunt Report on Human-Caused Climate Change

A new federal report released by the Trump administration concludes that the climate is changing and global temperatures are rising “primarily in response to human activities.”

The Climate Science Special Report published today by the U.S. Global Change Research Program is the first component of the next National Climate Assessment, which is congressionally mandated to be updated every four years. The last assessment was published in 2014. The new report concludes that it is “extremely likely” that human activities such as the burning of fossil fuels and deforestation have been “the dominant cause of the observed warming since the mid-20th century,” and that “there is no convincing alternative explanation” for the changes observed over the last century.

The report was prepared by hundreds of federal scientists, peer reviewed by the National Academy of Sciences, and deeply vetted by federal agencies. It sums up the most up-to-date science on the physical drivers of climate change, climate attribution, climate models and projections, changes in temperature and extreme weather, ocean acidification, and sea level rise, among other topics.

Global average surface air temperature has increased by about 1.8 degrees Fahrenheit over the last 115 years, the report notes, with the last three years being the warmest on record. Global average sea level has risen 7-8 inches since 1900 –half of that rise has happened in the last 25 years, and daily tidal flooding has gotten worse in more than 25 Atlantic and Gulf Coast states. The report also concludes that global sea levels would rise by 1-4 feet by 2100, but that “a rise of as much as 8 feet by 2100 cannot be ruled out.” Heavy rainfall, heat waves, and large wildfires are increasing in intensity and frequency in the U.S. and globally, the report finds.

The assessment underscores that climate impacts will continue to get worse unless nations cut greenhouse gas emissions. “Without major reductions in emissions,” it says, “the increase in annual average global temperature relative to preindustrial times could reach 9 degrees Fahrenheit or more by the end of this century.”

The report starkly contradicts the Trump administration’s stance on climate change, raising questions about how, if at all, it will be used in the government’s environmental decision-making. Since entering office, President Trump has worked to dismantle policies to address climate change, such as the Clean Power Plan, while at the same time bolstering support for fossil fuels.

“This is a federal government report whose contents completely undercut their policies, completely undercut the statements made by senior members of the administration,” Phil Duffy, the director of the Woods Hole Research Center, told The Washington Post.

(left) Global annual average temperature between 1980–2016 relative to 1901-1960 average. (right) Surface temperature change (in °F) for the period 1986–2016 relative to 1901–1960.U.S. Global Change Research Program